Protective device



April zz, 1930. 7 QCSINGLETON 1,755,970

PROTECTIVE DEVICE Filed Oct. 13. l926 Inventor Harold C. Singleton,

His Attorney.

' from the furnace so t at light from the flames Patented Apr. 1930 UNITED i STATES {PATENT OFFICE! c. smarizrou, or scorn, NEW YORK, ,AiSSIGNOR 'ro E ERAL unncrrarc' comrm, A conroiwrrou or raw roux I I rnorricrrvnnuvrcn Application nieii October13, 1926. Serial No. 141,397.

My present'invention relatestoprotective devices and more particularly to devices adaptedfor'use in connection with fluid fuel burning furnaces, provided with automatic ignition. In the employment. of such devices '.the automatic ignition sometimes fails to l :work, and as a result damage caused directly or indirectly by the escape of the fuel.

It is one of the ob e cts of my invention to provide means for automatically interrupting the supply of fuel to a burner when the automatic. ignition fails.

The novel features which I believe tobe characteristic of my invention are set forth in the appended claim. My invention itself,

however, will best be understoodfrdmreference to the following specification taken n connection with the accompanying drawing "in which Fig. 1 shows partly in elevation and artly in section an assembled oil burning ace, electric driven] blower and control I means embodying the features of my invention, while Fig. 2 shows diagrammatically a circuit organization for efi'ectingcontrol of 2 the electric motor and thereby the control of 1 the fuel suppliedto the furnace. The furnace 1, indicated in Fig. 1 of the drawing, includes a combustion chamber 2 and a burner, not shown. A. blower pipe or mixing tube 3 is connected at one end to the burner and at the other end to a blower 4 driven by an electric motor 5. Y The mixin tube 3isconnected to an oil supply throng pipe 6, and when blower 4 is in operation, oil is drawn through pipe 6 ,and supplied to the furnace burner. 1

In order to control the sup y of fuelto the burner a light sensitive cell in thepresent instance a photoelectric cell,is mounted at the end of the tube 3, which is remote may be directed on to the cell Without causing it to be damaged by the heat of the furnace. The cell 7 and electric discharge device 8 controlled thereb are mounted in a container 9, which may suitable manner at theendof the mixing t1] z. The circuit arrangement whereby the s11 ply of fuel to the burner may be controlled-1s one of the contacts -11' ofa relay 12 and.

' adapted to automatically openand close the tive potential or bias will be supplied to the r 'to the motor 5 through the high resistance supported in anyshown in Fig. 2 in whichan alternating cur-v reht'source ofsupply is indicated at 10. Mo'- 1 tor I5 is connected to the source 10 through through a'pair of parallel connected switches 13, and 14, one of which, 13, is of low resistance and the other of-which, 14, is a high resistance thermostatic switch. Switch '13 is normally held in close'dpos'ition by means of a spring 15., Relay 12 is'energized from an alternating current source through a circuit comprising a secondary windin' 16 of transformer 17, and a thermostatic 'switch 18 motor circuit in accordance with the. room temperature it is desired to maintain; Switch 113 is controlled'by a winding 19 connected in the output circuit of the electric'dischar e device 8, the latter including the usual ano e,

filamentary electrode and control element or 73' grid 20. The filamentary; electrode is supplied with heating current from the transformer 17 andltS ClI CIllt is completedthrough a contact 21 on relay 12 so that it will be ener giz ed or deenergized simultaneously with the 'energiz ati-on and deenergization of motor 5.-

Thephotoelectric cell 7 is connected to one of the secondary windings of transformer 17 and-to the grid 20 in such a manner that when light from the burner is dire ted on to the light sensitive surface of the cell, a negagrid element 20. This-potential is sufliciently high to prevent flow of current in the output circuit of the discharge device 8 and as a result switch 13. will be maintained in closed position by the'action of the spring 15. If for any reason the burner flame should be ex tinguished the light sensitive cell 7 would become deenergized, the negative potential would be removed, from the id 20, and as :a result current would flow in t e output circuit of the discharge device. 8 and energize coil 19 Y to openswitch 13. Current would now flow thermostatic switch 14, and after a period of time, depending on the setting of switch 14, the contacts of-the switch'wouldseparate and one of them would be locked in 0 en position I by meansof a latch 22. Therea r, in order to initiate operation of the motor 5, it would be necessary to manually unlatch switch 14.

Normally, since switch 13 is of very low resistance comparedto switch 14, the former will'act as a short circuit for switch "14 so that practically no current'will flow through the latter switch and it will remain in :closed position during'the normal operation ofmo:

burning furnaces. In the latter type of fur- While I have indicated-an arrangement for controlling the fuel supply by means of a blower. motor, obviously a motor operated valve in the. fuel supply pipe could be controlled instead of the blower ifdesired. The invention is moreover not limited to oil burners but is equallyadapted for use in'gas nace, however, a valve in the supply pipe would be controlled rather than a blower as in the present case.

What I claim as new and desire to secure by Letters Patentof the United States is An oil burner construction comprising a fan housing having a projecting nozzle portion, an air tube secured to said nozzle portion and opening thereinto, a combustion chamber into which the other end of said air tube opens, means for supplying fuel to said air tube, a housing secured to said nozzle portion and opening thereinto in alignment with the ends of said air tube and a flame responsive device in said housing whereby said flame responsive device is exposed to direct radiations from the burner flame.

In witness whereof, I have hereunto set III hand this 12th day of October 1926.

'HAROLD C. SINGLETON. 

